89-91 - Polskie Stowarzyszenie Biomateriałów

oth tests the differences between groups are not statistic
significant. The specimen no.5 shows the excessive values
in the nanoindentation. We did not find their cause, hence
we excluded it from the calculation of the mean elastic
modulus.
acknowledgements
The research project has been supported by the research
plan MSM 6840770012 “Transdisciplinary research in the
field of the biomedical engineering II”.
References
[1] J. Vondrova, P. Ruzicka, R. Sedlacek, et al., The Effect of Alcohol
Administration on the Bone Mechanical Properties. Proceedings of
the 22nd DAS, Parma (2005), 106-107.
[2] Y. H. An, R. A. Draughn, Mechanical Testing of Bone and the
Bone-Implant Interface, CRC Press LLC, Boca Raton, FL, 2000,
263.
expeRimental assessment
of IonIzIng RadIaTIon loW
doSES ImPaCT on TEETh
Development
N.N.CHESHKO, H.A.BERLOV, I.O.POHODENKO-CHUDAKOVA*
byeloruSSiAn StAte MedicAl uniVerSity, MinSK, belAruS
33-239, PuShKin AV.; Po box 190;
220092, MinSK, belAruS
*MAilto: iP-c@yAndex.ru
[Engineering of Biomaterials, 89-91, (2009), 8-9]
Introduction
Scientific grounds of solving post-Chernobyl medical,
biological, ecological, economic, social and other problems
remain as an important task for researchers working in different
fields of science.
Our research purpose is to study ionizing radiation low
doses (IRLD) in the laboratory experiment.
materials and methods
The experiments were carried out on 27 not thoroughbred
white female rats. They and their litter were irradiated
at the Institute of Radiobiology NAS RB by the «Gammarid-192/120
unit» (Gamma-defectoscope «Gammarid»
manufactured by the «Isotop» Enterprise, Leningrad) unit
at 110mR/h exposition power from the 1st gestation day up
to material selection on the 16th, 18th, 20th gestation day
and on the 1st and 3rd postnatal day. The absorbed dose
was 0,38–0,56Gy. The controls were not irradiated.
The specimens were fixed in 10% neutral formalin then
embedded in paraffin according to the standard method.
Sagittal «serial-selective» sections [1] were stained with
hematoxylin and eosin, picrofuchsin after van Gieson sum
content of DNA and RNA, which was evaluated by 5-mark
scale, revealed by the method of Einarson, elastic fibers
- by Hart, argyrophil ones - by Bilshovsky (H.Berlov’s
modification) [2].
Proliferative activity was determined according to the
method of A.Kazantseva [3]. The number of cellular layers
also was counted. The square, thickness and length of teeth
germs (TGs) were measured with «Bioscan – AT» (Model
was constructed in Central Scientific-Research Laboratory,
Medical Institute, Minsk) automatic image analyser. The
measurements were carried in each case of control and
experiment 10 times as a minimum. In all, 8329 histological
specimens of foetuses’ and new-born rats’ heads were
prepared, 2197 of them showing tooth germs. The data were
analysed by variation statistics with the Student’s test.
Results
While studying IRLD impact on odontogenesis we have
revealed some unknown before structures in tooth germs.
Thus, we described «concentric structures» in dental lamina
and in the inner enamel epithelium, its appearance was
delayed in experimental foetuses by IRLD action; pillowlike
thickenings in the inner enamel epithelium in controls;
inverted into mesenchyme dental buds in experimental rats’
foetuses, focal mesenchyme cell invasion into oral cavity.
We also have described undermembrane (underenameloblast)
cellular layer for the first time. Cyst formation due
to radiation exposure was revealed in the inner enamel
epithelium.
IRLD suppressed considerably the proliferative activity
of tooth germ cells. Total mitotic index in all age animals’
groups turned out to be lower than the respective indices in
the controls. Thus, in the experimental 16-day old foetuses
these values were 7,61±1,32‰, in the controls 25,84±0,45‰
(p